Bangkok takes over a 3D-printed canal footbridge that SCG built in two and a half months

BANGKOK, Oct. 31, 2025 — Bangkok Governor Chadchart Sittipunt formally received a pedestrian bridge over the Ong Ang canal that Siam Cement Group designed and built with 3D-printed concrete. Here's what happened, what it cost, and what went wrong.

Cost and outcome (as of Nov. 28, 2025)

Outcome: Bridge handed over to the Bangkok Metropolitan Administration at 7 a.m. on Oct. 31, 2025, after two and a half months of construction. (Bangkok Metropolitan Administration PR office, Oct. 31, 2025)
Cost: Not published by the city or SCG.
Materials claim: SCG says its "Generation 3" low-carbon cement cuts CO₂ emissions by more than 30%; that's the company's figure. (Bangkok Metropolitan Administration PR office, Oct. 31, 2025)

The handover

The bridge crosses Khlong Ong Ang between the Damrong Sathit and Phanuphan bridges in Phra Nakhon district, the city's PR office says. The governor said it took just two and a half months to build and showed that the city can raise its efficiency, "using the same resources but getting more output." He said Bangkok can't move forward on bureaucracy alone and needs partners in business, academia and the public. (Bangkok Metropolitan Administration PR office, Oct. 31, 2025; Daily News, Oct. 31, 2025)

Time Out Bangkok called it the city's first 3D-printed canal bridge, a collaboration between the city and SCG under the concept "Thai Innovation Bridge for a Sustainable City," and pointed readers to the stretch near MRT Sam Yot station. (Time Out Bangkok, Oct. 31, 2025)

What SCG says it used

Thammasak Sethaudom, SCG's president and CEO, said the bridge combines 3D concrete printing with high compressive strength, high-performance concrete (HPC) that's stronger than ordinary concrete, and SCG's "Generation 3" low-carbon cement, which he said cuts carbon dioxide emissions by more than 30%. He said SCG was proud to design and build the bridge with the city using innovation "developed by Thai people," and that it hands the bridge over for public use. (Bangkok Metropolitan Administration PR office, Oct. 31, 2025; Daily News, Oct. 31, 2025)

How it was engineered

The architects, CPAC CS, say the narrow canal corridor in Bangkok's dense old town limited site access. So the bridge was prefabricated off-site in 19 modular segments of about 1.5 tonnes each, and installed in a single day with a small crane. The printed parts serve as both deck and balustrade, are reinforced with HPC and carry a live load of 500 kg/m², they say. The project was commissioned under the city's canal revitalization program as a compact landmark that would improve mobility with minimal impact on the surrounding community. (architects' project description, via Jidipi)

ArchDaily lists the bridge at 40 m², with CPAC CS as architect and SCG as manufacturer. The architects describe the mix as LC3 concrete, which replaces part of the cement with calcined clay, and note that Ong Ang was long a centre of pottery trading. The canal once served as the city's defensive moat. (ArchDaily, Nov. 28, 2025; architects' project description, via Jidipi)

What went wrong

Hard site. The narrow corridor and limited access in the old town constrained both design and construction, the architects say, which is why the bridge was printed off-site. (architects' project description, via Jidipi)
Mixed descriptions. SCG's executive calls the cement "Generation 3"; the architects' text calls it LC3 concrete. Neither gives a measured CO₂ figure for this bridge. (Bangkok Metropolitan Administration PR office, Oct. 31, 2025; architects' project description, via Jidipi)
No price tag. Neither the city nor SCG has said what the bridge cost or who paid how much.
What we don't know yet: whether the city plans more printed canal bridges, and what this one cost against a conventional footbridge.

Our follow-up question for The Bangkok Metropolitan Administration

What did the Ong Ang bridge cost, who paid for it, and will the city use printed segments on other canal crossings?

Sources

Bangkok Metropolitan Administration PR office, handover of the SCG Ong Ang canal bridge (in Thai), Oct. 31, 2025. pr-bangkok.com
Daily News (Thailand), report on the Ong Ang canal bridge (in Thai), Oct. 31, 2025. dailynews.co.th
Time Out Bangkok, “You're looking at Bangkok's first 3D-printed canal bridge,” Oct. 31, 2025. timeout.com
ArchDaily, “OngAng 3D Concrete Printing Bridge / CPAC CS,” Nov. 28, 2025. archdaily.com
Jidipi, “OngAng 3D Concrete Printing Bridge” (architects' description). architectures.jidipi.com

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